Double disconnect transmission reverser with disconnect synchronizer

ABSTRACT

A transmission reverser for reversing a direction of an output gear carried by an output shaft includes a reverse shaft, a reverse clutch mounted about the reverse shaft and having engaged and disengaged conditions, and a reverse disconnect synchronizer mounted about the reverse shaft and having engaged and disengaged conditions. When the reverse clutch and the reverse disconnect synchronizer are in the engaged conditions, the reverse shaft rotates the output gear in a reverse direction of rotation opposite a direction of rotation of the output shaft. When the reverse disconnect synchronizer is in the disengaged condition, the reverse clutch is disconnected from the output gear.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This is a continuation-in-part application of pending application Ser.No. 15/049,629, filed Feb. 22, 2016.

STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to transmissions having areverser for changing the direction of a vehicle.

BACKGROUND OF THE DISCLOSURE

Transmissions are used in vehicles or work machines such as,agricultural, construction, off-road, and industrial machines, forexample. Transmissions used in work machines typically provide a largenumber of gear ratios for propelling the vehicle. A transmission mayinclude a reverser for changing directions of the vehicle. The reversercan be located near the output of the transmission. In some priordesigns, a countershaft reverser rotates at high speeds when the vehicleis operating at high forward speeds. This can cause high windage in thereverse clutch. This can also cause gyroscopic flutter, in which thefriction disk or the separator plate becomes dynamically unstablecreating drag in the clutch. This drag can cause the disengaged clutchto experience a thermal failure. In other prior designs, a synchronizedreverser goes to neutral when switching between forward and reversecausing a pause in the acceleration.

SUMMARY OF THE DISCLOSURE

This summary is provided to introduce a selection of concepts that arefurther described below in the detailed description and accompanyingdrawings. This summary is not intended to identify key or essentialfeatures of the appended claims, nor is it intended to be used as an aidin determining the scope of the appended claims.

According to an aspect of the present disclosure, a transmissionreverser for reversing a direction of an output gear carried by anoutput shaft may include a reverse shaft, a reverse clutch mounted aboutthe reverse shaft and having engaged and disengaged conditions, and areverse disconnect synchronizer mounted about the reverse shaft andhaving engaged and disengaged conditions. When the reverse clutch andthe reverse disconnect synchronizer are in the engaged conditions, thereverse shaft rotates the output gear in a reverse direction of rotationopposite a direction of rotation of the output shaft. When the reversedisconnect synchronizer is in the disengaged condition, the reverseclutch is disconnected from the output gear.

According to another aspect of the present disclosure, a transmissionreverser for reversing a direction of an output gear carried by anoutput shaft may include a reverse shaft extending along a rotationaxis, reverse gears mounted about the reverse shaft, a reverse clutchmounted about the reverse shaft having engaged and disengaged conditionsand connecting one of the reverse gears with the reverse shaft in theengaged condition, and a reverse disconnect synchronizer having engagedand disengaged conditions connecting another of the reverse gears withthe reverse shaft in the engaged condition. The reverse disconnectsynchronizer includes a hub mounted about the reverse shaft and defininga piston chamber. An actuator piston within the piston chamber is drivenby fluid pressure in at least one direction along the rotation axis ofthe reverse shaft. A shift collar mounted to the actuator piston engagesthe reverse gear in an engaged state. When the reverse clutch and thereverse disconnect synchronizer are in the engaged conditions, thereverse shaft rotates the output gear in a reverse direction of rotationopposite a direction of rotation of the output shaft. When the reversedisconnect synchronizer is in the disengaged condition, the reverseclutch is disconnected from the output gear.

According to another aspect of the present disclosure a transmissionreverser for reversing a direction of an output gear carried by anoutput shaft may include a reverse shaft extending along a rotationaxis, reverse gears mounted about the reverse shaft, a reverse clutchmounted about the reverse shaft having engaged and disengaged conditionsand connecting one of the reverse gears with the reverse shaft in theengaged condition, and a reverse disconnect synchronizer having engagedand disengaged conditions and connecting another of the reverse gearswith the reverse shaft in the engaged condition. The reverse disconnectsynchronizer includes an actuator piston having a first annular surfacewith a first interlock feature, and a shift collar engaging the reversegear in an engaged state and having a second annular surface with asecond interlock feature configured to engage the first interlockfeature of the actuator piston. The shift collar is connected to theactuator piston by overlapping radial surfaces of the first and secondinterlock features when the first and second annular surfaces arearranged concentrically. When the reverse clutch and the reversedisconnect synchronizer are in the engaged conditions, the reverse shaftrotates the output gear in a reverse direction of rotation opposite adirection of rotation of the output shaft. When the reverse disconnectsynchronizer is in the disengaged condition, the reverse clutch isdisconnected from the output gear.

These and other features will become apparent from the followingdetailed description and accompanying drawings, wherein various featuresare shown and described by way of illustration. The present disclosureis capable of other and different configurations and its several detailsare capable of modification in various other respects, all withoutdeparting from the scope of the present disclosure. Accordingly, thedetailed description and accompanying drawings are to be regarded asillustrative in nature and not as restrictive or limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description of the drawings refers to the accompanyingfigures in which:

FIG. 1 is a perspective cutaway view of a transmission, according to oneembodiment;

FIG. 2 is a rear perspective view of a transmission, according to oneembodiment;

FIG. 3 is a side sectional view of a reverser, according to oneembodiment;

FIG. 4 is a side sectional view of a reverser illustrating the powerpath for the forward mode, according to one embodiment;

FIG. 5 a side sectional view of a reverser illustrating the power pathfor the reverse mode, according to one embodiment;

FIG. 6 is a schematic diagram of a control strategy for a transmission,according to one embodiment;

FIG. 7 is a flow diagram illustrating a method of shifting betweenforward and reverse directions in a transmission reverser, according toone embodiment;

FIG. 8 is a flow diagram illustrating a method of shifting betweenreverse and forward directions in a transmission reverser, according toone embodiment;

FIG. 9 is a side sectional view of a reverser illustrating the powerpath for the forward mode, according to a second example embodiment;

FIG. 10 a side sectional view of a reverser illustrating the power pathfor the reverse mode, according to the second example embodiment;

FIG. 10A is an enlarged view of an example disconnect synchronizerarrangement for a reverser, according to the second embodiment;

FIG. 10B is a detailed view of area 10B-10B of an interface between anactuator piston and a shift collar of the disconnect synchronizer shownin FIG. 10A;

FIG. 11 is a schematic diagram of a control system for a transmissionaccording to the second example embodiment;

FIG. 11A is a schematic diagram of a control strategy for atransmission, according to the second embodiment;

FIG. 12 is a flow diagram illustrating an example start-up sequence fora transmission reverser, according to the second embodiment;

FIG. 13 is a flow diagram illustrating an example method of shiftingbetween forward and reverse directions in a transmission reverser,according to the second embodiment;

FIG. 13A is a flow diagram illustrating an example logic subroutine forcontrolling engagement of a disconnect synchronizer in the method ofFIG. 13;

FIG. 14 is a flow diagram illustrating an example method of shiftingbetween reverse and forward directions in a transmission reverser,according to the second embodiment;

FIG. 14A is a flow diagram illustrating an example control logicsubroutine for controlling engagement or disengagement of the disconnectsynchronizer in the method of FIG. 14; and

FIG. 14B is a flow diagram illustrating an example control logicsubroutine for detecting a fault in disengagement of the disconnectsynchronizer in the method of FIG. 14.

Like reference numerals are used to indicate like elements throughoutthe several figures.

DETAILED DESCRIPTION

The embodiments disclosed in the above drawings and the followingdetailed description are not intended to be exhaustive or to limit thedisclosure to these embodiments. Rather, there are several variationsand modifications which may be made without departing from the scope ofthe present disclosure.

FIG. 1 illustrates a transmission 100 for a vehicle or work machine,such as a tractor, for example. The present disclosure also applies toother powered or motorized vehicles, machines, or equipment. Thetransmission 100 includes a housing 102 forming an interior, whichprovides an enclosure for one or more transmission components including,but not limited to, shafts, gears, clutches, and synchronizers. Thetransmission 100 may include a transmission reverser apparatus 110,which shifts the transmission output between forward and reverse. Thereverser 110 can be integral with or separate from the transmission 100.

FIGS. 2 and 3 illustrate a transmission 100 having a reverser apparatus110, which may include one or more of the following components. Thetransmission 100 may include an output shaft 112, an idler shaft 114,and a counter shaft 116 rotatably connected to the transmission housing102. The transmission 100 may include a first reverse gear 120 and anoutput gear 122 positioned or mounted on the output shaft 112. Theoutput gear 122 is operatively connected to the drivetrain of a vehicleproviding power to ground engaging apparatus such as wheels or tracks.The transmission may include an idler gear 124 positioned or mounted onthe idler shaft 114. The transmission may include a second reverse gear126 and a third reverse gear 128 positioned or mounted on the countershaft 116. The transmission 100 may include a forward clutch 130, whichoperably connects or couples the output gear 122 with the output shaft112 in an engaged position or condition. The forward clutch 130 may beconnected to or mounted about the output shaft 112.

The transmission 100 may include a reverse clutch 132, which operablyconnects or couples the second reverse gear 126 with the counter shaft116 in an engaged position or condition. The reverse clutch 132 may beconnected to or mounted about the counter shaft 116. In anotherembodiment, the reverse clutch 132 operably connects or couples thefirst reverse gear 120 with the output shaft 112. The reverse clutch 132may be connected to or mounted about the output shaft 112. In thisembodiment, the output shaft 112 rotates independently of the firstreverse gear 120, the idler gear 124, and idler shaft 114 when thereverse clutch 132 is disengaged. The transmission 100 may include adisconnect clutch 134, which operably connects or couples the thirdreverse gear 128 with the counter shaft 116 in an engaged position orcondition. The disconnect clutch 134 may be connected to or mountedabout the counter shaft 116. The first reverse gear 120 engages ormeshes with the idler gear 124, which engages or meshes with the secondreverse gear 126. The third reverse gear 128 engages or meshes with theoutput gear 122. The transmission 100 may include a countershaft brake136, which reduces or stops the rotation of the counter shaft 116 in anengaged position or condition. In some embodiments, the countershaftbrake 136 can impede or prevent the counter shaft 116 from rotating.This can impede or prevent the reverse clutch 132 from rotating when thecountershaft brake 136 is engaged.

FIG. 4 illustrates a power path or flow for a forward mode F through thereverser apparatus 110. In the forward mode F, the forward clutch 130 isengaged causing the output gear 122 to rotate with the output shaft 112,the countershaft brake 136 is engaged impeding or preventing the countershaft 116 from rotating, and the reverse clutch 132 and the disconnectclutch 134 are disengaged. When the countershaft brake 136 is engaged,this can also impede or prevent the reverse clutch 132 from rotating.The idler shaft 114 rotates opposite to the output shaft 112 based uponthe ratio of the first reverse gear 120 to the idler gear 124. Thesecond reverse gear 126 rotates about the counter shaft 116 in adirection opposite of the idler shaft 114 based upon the ratio of theidler gear 124 to the second reverse gear 126. At slow forward speeds,the countershaft brake 136 can be disengaged and the disconnect clutch134 can be engaged causing the counter shaft 116 to rotate in theopposite direction as the output shaft 112 based upon the ratio of theoutput gear 122 to the third reverse gear 128. In some embodiments, slowforward speeds are at or below about 5 kph, 4 kph, 3 kph, 2 kph, or 1kph.

FIG. 5 illustrates a power path or flow for a reverse mode R through thereverser apparatus 110. In the reverse mode R, the reverse clutch 132and the disconnect clutch 134 are engaged causing the output gear 122 torotate in a direction opposite the output shaft 112. The forward clutch130 and the countershaft brake 136 are disengaged. The output gear 122rotates opposite to the counter shaft 116 based upon the ratio of thethird reverse gear 128 to the output gear 122. The counter shaft 116rotates opposite to the idler shaft 114 based upon the ratio of theidler gear 124 to the second reverse gear 126. The idler shaft 114rotates opposite the output shaft 112 based upon the ratio of the firstreverse gear 120 to the idler gear 124. As a result, the counter shaft116 rotates in the same direction as the output shaft 112.

FIG. 6 illustrates a control strategy for a transmission, which may beimplemented in one or more of the embodiments described herein anddepicted in the various FIGURES. When the transmission is in the reversemode R, the reverse clutch 132 and the disconnect clutch 134 are engagedand the forward clutch 130 and countershaft brake 136 are disengaged.When switching between the reverse mode R and the forward mode F, eventscan occur in the following order: the reverse clutch 132 is disengaged,the forward clutch 130 is engaged, the disconnect clutch 134 isdisengaged, and the countershaft brake 136 is engaged. The reverseclutch 132 and the forward clutch 130 can be engaged and disengaged atslow reverse speeds, slow forward speeds, or when the vehicle is notmoving.

When the transmission is in the forward mode F, the forward clutch 130and countershaft brake 136 are engaged and the reverse clutch 132 andthe disconnect clutch 134 are disengaged. When switching between theforward mode F and the reverse mode R, events can occur in the followingorder: the countershaft brake 136 is disengaged, the disconnect clutch134 is engaged, the forward clutch 130 is disengaged, and the reverseclutch is engaged. The disconnect clutch 134 and the countershaft brake136 can be engaged and disengaged at slow forward speeds or when thevehicle is not moving.

FIG. 7 illustrates a flow chart for a method of shifting between aforward mode and a reverse mode in a transmission reverser, according toone embodiment, which may be implemented in one or more of theembodiments described herein and depicted in the various FIGURES. Atstep 200, the method starts.

At step 202, the transmission is in the forward mode F with the forwardclutch 130 and the countershaft brake 136 in the engaged conditions.

At step 204, the transmission receives a command to switch from theforward mode F to the reverse mode R.

At step 206, the countershaft brake 136 disengages which allows thecounter shaft 116 to rotate.

At step 208, the disconnect clutch 134 engages which releasably connectsor couples the third reverse gear 128 to the counter shaft 116 causingthe counter shaft 116 to rotate in the opposite direction as the outputshaft 112 based upon the engagement of the third reverse gear 128 withthe output gear 122.

At step 210, the forward clutch 130 disengages which disconnects theoutput gear 122 from the output shaft 112 allowing the output gear 122to rotate independently of the output shaft 112.

At step 212, the reverse clutch 132 engages which releasably connects orcouples the second reverse gear 126 to the counter shaft 116 causing thecounter shaft 116 to rotate in the same direction as the output shaft112 based upon the engagement of the first reverse gear 120 mounted onthe output shaft 112 with an idler gear 124 mounted on an idler shaft114 and the engagement of the idler gear 124 with the second reversegear 126.

In an alternate step 212, the reverse clutch 132 engages whichreleasably connects or couples the first reverse gear 120 to the outputshaft 112 causing the counter shaft 116 to rotate in the same directionas the output shaft 112 based upon the engagement of the first reversegear 120 with the idler gear 124 mounted on the idler shaft 114 and theengagement of the idler gear 124 with the second reverse gear 126mounted on the counter shaft 116.

At step 214, the method of shifting between a forward mode and a reversemode in a transmission reverser completes, according to one embodiment.In other embodiments, one or more of these steps or operations may beomitted, repeated, or re-ordered and still achieve the desired results.

FIG. 8 illustrates a flow chart for a method of shifting between areverse mode and a forward mode in a transmission reverser, according toone embodiment, which may be implemented in one or more of theembodiments described herein and depicted in the various FIGURES. Atstep 200, the method starts.

At step 202, the transmission is in the reverse mode R with the reverseclutch 132 and the disconnect clutch 134 in the engaged conditions.

At step 204, the transmission receives a command to switch from thereverse mode R to the forward mode F.

At step 206, the reverse clutch 132 disengages which disconnects thesecond reverse gear 126 from the counter shaft 116, or disconnects thefirst reverse gear 120 from the output shaft 112, allowing the countershaft 116 to rotate independently of the output shaft 112.

At step 208, the forward clutch 130 engages which releasably connects orcouples the output gear 122 to the output shaft 112 causing the outputgear 122 to rotate with the output shaft 112.

At step 210, the disconnect clutch 134 disengages which disconnects thethird reverse gear 128 from the counter shaft 116 allowing the countershaft 116 to rotate independently of the output gear 122.

At step 212, the countershaft brake 136 engages which slows or stops therotation of the counter shaft 116. In some embodiments, the countershaftbrake 136 can then impede or prevent the counter shaft 116 fromrotating.

At step 214, the method of shifting between a reverse mode and a forwardmode in a transmission reverser completes, according to one embodiment.In other embodiments, one or more of these steps or operations may beomitted, repeated, or re-ordered and still achieve the desired results.

At step 214, the method of shifting between a reverse mode and a forwardmode in a transmission reverser completes, according to one embodiment.In other embodiments, one or more of these steps or operations may beomitted, repeated, or re-ordered and still achieve the desired results.

Another example embodiment of the transmission reverser disclosed hereinwill now be described. It will be understood that this embodiment of thetransmission reverser may be incorporated into a transmission for avehicle or work machine (or other equipment). For example, thetransmission 100 may incorporate this embodiment of the transmissionreverser and may have the same configuration as shown and described withrespect to FIGS. 1 and 2 above, unless specifically noted, including ahousing 102 forming an interior, which provides an enclosure for one ormore transmission components including, but not limited to, shafts,gears, clutches, and synchronizers. As in the prior example embodiment,this embodiment of the transmission reverser may be used to shift thetransmission output between forward and reverse, and may be integralwith or separate from the transmission 100.

FIGS. 9 and 10 illustrate a reverser apparatus 300, which may includeone or more of the following components, including an output shaft 302,an idler shaft 304, and a reverse shaft in the form of a counter shaft306 extending along a rotation axis “A,” all of which are rotatablyconnected to the transmission housing 102. The transmission 100 or thereverse apparatus 300 may include a first reverse gear 310 and an outputgear 312 positioned or mounted on the output shaft 302. The output gear312 may be operatively connected to the drivetrain of a vehicleproviding power to ground engaging apparatus such as wheels or tracks.The transmission 100 or the reverser apparatus 300 may include an idlergear 316 positioned or mounted on the idler shaft 304, and a secondreverse gear 318 and a third reverse gear 320 positioned or mounted onthe counter shaft 306. The transmission 100 or the reverser apparatus300 may include a forward clutch 330, which operably connects or couplesthe output gear 312 with the output shaft 302 in an engaged position orcondition. The forward clutch 330 may be connected to or mounted aboutthe output shaft 302. The transmission 100 or the reverser apparatus 300may include a reverse clutch 332, which operably connects or couples thesecond reverse gear 318 with the counter shaft 306 in an engagedposition or condition. Like the preceding embodiment, in thisembodiment, the reverse clutch 332 may be connected to or mounted aboutthe counter shaft 306, such that the counter shaft 306 rotatesindependently of the first reverse gear 310, the idler gear 316, andidler shaft 304 when the reverse clutch 332 is disengaged. In anotherembodiment, the reverse clutch 332 operably connects or couples thefirst reverse gear 310 with the output shaft 302, in which case thereverse clutch 332 may be connected to or mounted about the output shaft302, such that the output shaft 302 rotates independently of the firstreverse gear 310, the idler gear 316, and idler shaft 304 when thereverse clutch 332 is disengaged.

The transmission 100 or the reverser apparatus 300 of this embodimentincludes a disconnect synchronizer 340, which operably connects orcouples the third reverse gear 320 with the counter shaft 306 in anengaged position or condition. The disconnect synchronizer 340 may beconnected to or mounted about the counter shaft 306. The first reversegear 310 engages or meshes with the idler gear 316, which engages ormeshes with the second reverse gear 318. The third reverse gear 320engages or meshes with the output gear 312. In this embodiment, thetransmission 100 or the reverser apparatus 300 may omit a countershaftbrake used in the preceding embodiment to reduce or stop the rotation ofthe counter shaft 306 in an engaged position or condition, and therebyimpede or prevent the reverse clutch 332 from rotating. Alternatively, acountershaft brake may be incorporated in the transmission 100 or thereverser apparatus 300 of this embodiment, such as countershaft brake136, and may be used for the noted purpose.

FIG. 9 illustrates a power path or flow for a forward mode F through thereverser apparatus 300. In the forward mode F, the forward clutch 330 isengaged causing the output gear 312 to rotate with the output shaft 302,and the reverse clutch 332 (and at times the disconnect synchronizer340) are disengaged. (If present, the countershaft brake may be engagedimpeding or preventing the counter shaft 306 and the reverse clutch 332from rotating.) The idler shaft 304 rotates opposite to the output shaft302 based upon the ratio of the first reverse gear 310 to the idler gear316. The second reverse gear 318 rotates about the counter shaft 306 ina direction opposite of the idler shaft 304 based upon the ratio of theidler gear 316 to the second reverse gear 318. At slow forward speeds,the disconnect synchronizer 340 can be engaged causing the counter shaft306 to rotate in the opposite direction as the output shaft 302 basedupon the ratio of the output gear 312 to the third reverse gear 320. (Ifpresent, the countershaft brake would be disengaged.) As with thepreceding embodiment, slow forward speeds may be at or below about 5kph, 4 kph, 3 kph, 2 kph, or 1 kph.

FIG. 10 illustrates a power path or flow for a reverse mode R throughthe reverser apparatus 300. In the reverse mode R, the reverse clutch332 and the disconnect synchronizer 340 are engaged causing the outputgear 312 to rotate in a direction opposite the output shaft 302. Theforward clutch 330 (and if present, the countershaft brake) aredisengaged. The output gear 312 rotates opposite to the counter shaft306 based upon the ratio of the third reverse gear 320 to the outputgear 312. The counter shaft 306 rotates opposite to the idler shaft 304based upon the ratio of the idler gear 316 to the second reverse gear318. The idler shaft 304 rotates opposite the output shaft 302 basedupon the ratio of the first reverse gear 310 to the idler gear 316. As aresult, the counter shaft 306 rotates in the same direction as theoutput shaft 302.

The disconnect synchronizer may be configured in various ways. Forexample, certain known synchronizers are engaged and disengaged bymovement of a shift rail and fork arrangement, which may be manually orsemi-automatically actuated. Generally, in such cases, one or more forkelements ride along one or more shift rails to displace a synchronizerelement into engagement with a gear of the transmission (e.g., bymeshing synchronizer splines with gear splines). The synchronizer iscoupled for co-rotation with the shaft, and thus, the engagement of thesynchronizer with the gear also couples the gear to the shaft forco-rotation, thereby incorporating the gear into the rotational power(or torque) path from the power source (e.g., an engine). A blockingmember may be arranged between the synchronizer element and the gear toinhibit displacement until its splines are clocked to offset with thesplines of the gear. The engagement and disengagement of the gear maythus be largely, if not entirely, mechanical in the sense that the shiftrail actuates the synchronizer back and forth with respect to the gear.Certain other known synchronizers have been devised that use hydraulicpower to couple transmission gears to the output shaft. Some of theseuse a shift rail and fork assembly similar to that described above,although shift fork movement is effected hydraulically. Other systemseliminate the shift rail and fork arrangement entirely. Instead, thesesystems route hydraulic fluid into chambers that drive pistons todisplace shift collars into engagement with the gears. A shift collar isdisengaged from a gear by venting a pressure chamber so that one or morereturn springs acting on the piston can move the shift collar back to aneutral position. The reverse may be true as well in which the springapplies the engaging force to the shift collar, which is then disengagedhydraulically. Still other synchronizers may be used that are fullyelectro-hydraulically operated such that displacement of the shiftcollars into both engagement and disengagement positions is accomplishedby hydraulic power. Moreover, the disconnect synchronizer may be single-or double-sided, in which either one or two gears may be selectivelyengaged with the shaft.

By way of example, this embodiment of the reverser apparatus 300 will bedescribed with the disconnect synchronizer 340 being configured as asingle-sided (or “half”) forkless synchronizer that is hydraulicallyengaged and disengaged by spring force. Although not shown, it will beunderstood that the work vehicle, transmission 100 or the reverserapparatus 300 includes, or is in operational communication with, anelectrohydraulic system with one or more hydraulic pumps andelectrohydraulic valves operated by one or more controllers to controloperational modes of the transmission 100 or reverser apparatus 300.Generally, the example disconnect synchronizer 340 is operable toselectively couple the third reverse gear 320 to the counter shaft 306,and thereby the reverse clutch 332 to the output gear 312, depending onthe control logic associated with the operational mode of thetransmission, as noted above and described in detail below.

FIG. 10A illustrates the example half forkless hydraulic disconnectsynchronizer 340. The disconnect synchronizer 340 may be connected to ormounted about the counter shaft 306 by a drum 342 or the like that ismounted to the counter shaft 306 for co-rotation at all times, such asvia the mating splines or other mating toothed or multi-sided sectionsof the counter shaft 306 and the drum 342. The drum 342 defines astepped annular piston chamber 344 in which hydraulic fluid may bedirected in a controlled manner to move an actuator piston 346 along therotation axis A. The actuator piston 346 has a stepped outer peripheryto match the piston chamber 344 and is sealed (via O-rings or the like)at both stepped diameters. The shift collar 348 has an axially splinedinner diameter that mates with an axially splined periphery(circumference or circumferential segments) of a hub 350 that has anaxially splined inner diameter engaging splines on the counter shaft306. The hub 350 has open areas in which mount spring detentarrangements 352 (each with a spring 354, a ball 356 and a ball collar358) that are coupled to the hub 350 (e.g., by retaining pins of orattached to the ball collar 358). The balls 356 of the spring detentarrangements 352 ride in an annular groove 368 in the splined innerdiameter of the shift collar 348 and apply a spring force to a blockingring 370 when the shift collar 348 is initially shifted axially relativeto the hub 350. An annular body of the blocking ring 370 is disposedwithin an annular, open-faced pocket 372 in the hub 350 axially betweenthe third reverse gear 320 and the hub 350. The blocking ring 370rotates with the hub 350 but is permitted to “float” or rotate relativeto the hub 350 slightly, for example, through a pin and slot connection(not shown) of the blocking ring 370 to the hub 350. The blocking ring370 has a tapered inner periphery that mates with a tapered annulus orcone 374 that may be attached to or integrally formed with the thirdreverse gear 320. In certain embodiments, the taper of the blocking ring370 or the gear cone 374 may include (e.g., by adhesive bonding) a thinfriction ring 360 to aid in establishing a robust frictional connection,and cooling grooves (not shown) may be formed into the friction ring 360to aid in heat dissipation. The blocking ring 370 also has an axiallysplined outer ring (or ring segments) that engages with the splinedinner diameter of the shift collar 348. The drum 342, the actuatorpiston 346, the shift collar 348, the hub 350 and the blocking ring 370may each be an assembly of parts or a single, monolithic structure.Movement of the actuator piston 346 is biased against by one or moresprings 380 (e.g., Belleville springs) that are mounted within the drum342 axially between the actuator piston 346 and the hub 350.

The blocking ring 370 functions to reduce or prevent “gear clash” byblocking the splines of the shift collar 348 from engaging the splinesof the third reverse gear 320 when the projections of the splines of theshift collar 348 are not clocked or rotationally aligned with thevalleys of the splines of the third reverse gear 320. Specifically, asthe shift collar 348 is moved axially toward the third reverse gear 320by the actuator piston 346, the groove 368 in the splined inner diameterof the shift collar 348 will cam against the balls 356 to compress thesprings 354, and thereby apply an axial force against a radial face ofthe blocking ring 370. The axial force is an axial component of theradial force applied to the springs 354 by engagement of the balls 356and curved wall of the groove 368. The springs 354 push the blockingring 370 against the third reverse gear 320, more specifically, thetapered surface of the blocking ring 370 and the gear cone 374.Initially there will be a differential between the rotational speed ofthe blocking ring 370 (and thus the rest of the disconnect synchronizer340 and the counter shaft 306) and the third reverse gear 320. Thespring force biasing the blocking ring 370 against the third reversegear 320 along with the speed differential creates torque on theblocking ring 370, which causes it to rotate relative to the hub 350slightly (e.g., until the pin(s) meet the end(s) of the slot(s)), afterwhich it continues to co-rotate with the hub 350. This positions theblocking ring 370 in a position that interferes with the axial path ofthe shift collar 348. As the shift collar 348 continues to travel,tapered tooth points at the ends of the splines of the shift collar 348contact tapered tooth points of the splines of the blocking ring 370.The angled tips cam against each other and create rotational force ortorque on the blocking ring 370 tending to index and clear the blockingring 370 from the path of the splines of the shift collar 348. Thistorque is resisted by torque from the engagement of the blocking ring370 (or friction ring 360) and the gear cone 374, which is stillrotating at a different speed. Upon the third reverse gear 320 beingaccelerated or decelerated to match the disconnect synchronizer 300speed, the frictional torque with the gear cone 374 dissipates to allowthe splines of the shift collar 348 to pass between the splines of theblocking ring 370. If the third reverse gear 320 is not properly clockedwith the blocking ring 370, as the shift collar 348 travels further,tooth point contact between the shift collar 348 and the third reversegear 320 will create torque that indexes the blocking ring 370 slightly(as permitted by the pin and slot connection(s)) until the splines ofthe shift collar 348 can fully engage with the splines of the thirdreverse gear 320. The splines of the shift collar 348 will mate with thesplines of both the third reverse gear 320 and the hub 350simultaneously, thereby engaging the third reverse gear 320 with thecounter shaft 306. When the pressure in the piston chamber 344 is ventedsufficiently, the springs 380 will return the actuator piston 346 andthe shift collar 348 to the disengaged position in which the thirdreverse gear 320 is disengaged from the counter shaft 306.

FIG. 10B illustrates that the actuator piston 346 directly engages theshift collar 348 along an interlock interface formed between aninterlock features 388, 389 in annular surfaces 390, 391 of the actuatorpiston 346 and the shift collar 348. The shift collar 348 is connectedto the actuator piston 346 by overlapping radial surfaces 392, 393 ofthe interlock features 388, 389 when the annular surfaces 390, 391 arearranged concentrically. Coupling the interlock features 388, 389 mayconnect the shift collar 348 to the actuator piston 346 with relativerotational freedom, such as to allow for an angular indexing (e.g., 2-3degrees) of the shift collar 348 relative to the actuator piston 346 byproviding a small (e.g., half of a millimeter) difference in the radialdimensions. The radial surfaces 392, 393 of the interlock features 388,389 engage to prevent separation of the shift collar 348 from theactuator piston 346 in at least one axial direction, such as duringreturn to the disengaged position. The radial surfaces 392, 393 of theinterlock features 388, 389 may be oriented substantially perpendicularto the rotation axis A of the counter shaft 306 to provide a flatsurface and sharp corner for establishing and maintaining contactbetween the actuator piston 346 and the shift collar 348 duringretraction. Also, the annular surfaces 390, 391 of the actuator piston346 and the shift collar 348 may include undercut stress-relievingrecesses 394, 395 adjacent the radial surfaces 392, 393 of the interlockfeatures 388, 389. In various embodiments, the actuator piston 346 andthe shift collar 348 may be the same or different materials andmanufactured using the same or different processes. For example, theshift collar 348 may be heat treated carbonized steel, and the actuatorpiston 346 may be a quenched and tempered forged steel with no heattreatment. Further, the actuator piston 346 and the shift collar 348 maybe assembled directly to one another without fasteners or otherintermediary components, such as by a press-fit operation to engage theinterlock features 388, 389. As one example, the actuator piston 346 maybe pressed onto the shift collar 348, in which case the inner annularsurface 390 of the actuator piston 346 overlaps and engages the outerannular surface 391 of the shift collar 348. The actuator piston 346 andthe shift collar 348 may each include chamfered leading edges 396, 397(which convert axial forces to radial forces to open the actuator piston346), and the actuator piston 346 may include one or more peripheralnotches 398 at the chamfered leading edge 396 of its annular surface 390to facilitate flexing and relieve stress during the press-fit operationbelow material yield. It will be understood that other configurationsare possible and that the overlap and coupling of components may bereversed from that described.

FIG. 11 illustrates schematically control hardware and data flow for atransmission, which may be implemented with regard to the embodiment ofthe reverser apparatus 300. FIG. 11A illustrates a control strategy fora control system 400 of FIG. 11. When the transmission 100 is in thereverse mode R, the reverse clutch 332 and the disconnect synchronizer340 are engaged and the forward clutch 330 (and countershaft brake ifpresent) are disengaged. Generally, when switching between the reversemode R and the forward mode F, events can occur in the following order:the reverse clutch 332 is disengaged, the forward clutch 330 is engaged,the disconnect synchronizer 340 is disengaged (and if present, thecountershaft brake is engaged). The reverse clutch 332 and the forwardclutch 330 can be engaged and disengaged at slow reverse speeds, slowforward speeds, or when the vehicle is not moving. When the transmissionis in the forward mode F, the forward clutch 330 (and countershaft brakeif present) are engaged and the reverse clutch 332 (and at times thedisconnect synchronizer 340) are disengaged. Generally, when switchingbetween the forward mode F and the reverse mode R, events can occur inthe following order: any countershaft brake is disengaged, thedisconnect synchronizer 340 is engaged, the forward clutch 330 isdisengaged, and the reverse clutch 332 is engaged. The disconnectsynchronizer 340 (and the countershaft brake if present) can be engagedand disengaged at slow forward speeds or when the vehicle is not moving.

The control system 400 includes a vehicle, transmission or reverserapparatus controller 402 (or multiple controllers) that may beconfigured as a computing device with associated processor devices andmemory architectures, as a hard-wired computing circuit (or circuits),as a programmable circuit, as a hydraulic, electrical orelectro-hydraulic controller, or otherwise, so as to execute variouscomputational and control functionality with respect to the transmission100 or the reverser apparatus 300. The controller 402 and its variousmodules are each schematically represented by a single block. However,the controller 402, and its modules, can include any number ofprocessing devices, which can be distributed and interconnectedutilizing different communication protocols and memory architectures.Also, each block depicted may incorporate one or more additionalcomponents than that specified (e.g., a block representing a particularclutch or synchronizer may include an associated electrohydrauliccontrol valve). As used herein, the term module refers to any hardware,software, firmware, electronic control component, processing logic,and/or processor device, individually or in any combination, includingwithout limitation: application specific integrated circuit (ASIC), anelectronic circuit, a processor (shared, dedicated, or group) and memorythat executes one or more software or firmware programs, a combinationallogic circuit, and/or other suitable components that provide thedescribed functionality.

The controller 402 may be configured to receive input signals in variousformats (e.g., as hydraulic signals, voltage signals, current signals,and so on), and to output command signals in various formats (e.g., ashydraulic signals, voltage signals, current signals, mechanicalmovements, and so on). The controller 402 may be in electronic,hydraulic, mechanical, or other communication with various other systemsor devices of the vehicle, transmission or reverser apparatus. Forexample, the work vehicle controller 402 may be in electronic orhydraulic communication with various actuators, sensors, and otherdevices within (or outside of) vehicle, transmission or reverserapparatus, including various timers or clocks 410 and various sensors,such as speed sensors 412, 413, 414 and a pressure sensor 416 fordetermining the absolute or relative speeds or pressures of variouscomponents of the reverser apparatus 300 (e.g., the speed of the thirdreverse gear 320 with respect to the counter shaft 306 or variousdisconnect synchronizer components co-rotating therewith), and anoperator control 418. Various other devices and sensors (e.g.,temperature sensors) may be incorporated into the control system 400 andused by the controller 402 to process the disclosed control logic. Thevarious devices and sensors provide input or observe conditionsassociated with the transmission 100 or the reverser apparatus 300 andgenerate input signals or data that are communicated to the controller402. The controller 402 may be located onboard the vehicle, or atvarious remote locations. The controller 402 uses input from the variousdevices and sensors to control the state of engagement of variouscomponents of the transmission 100 or the reverser apparatus 300,including an input clutch 420, the forward clutch 330, the reverseclutch 332, the disconnect synchronizer 340, and a park brake or parkmode control 430. The input clutch 420 may be one or a combination ofmultiple clutches interposed between the engine and the output shaft 302to control power from the engine in one of various operational modes ofthe transmission 100. Various other devices (e.g., a countershaft brake)may be controlled by the control system 400.

In the illustrated embodiment, the controller 402 includes variousembedded modules or sub-modules that unitarily or collectively processthe input signals or data and provide output control commands to thedevices of the transmission 100 or reverser apparatus 300 according tothe control logic of the present disclosure. As may be appreciated, inother embodiments, the modules or sub-modules shown may be combinedand/or further partitioned. Specifically, the example controller 402includes a device control (DC) module 440 that interfaces with thevarious components and devices of the transmission 100 or reverserapparatus 300, namely, for example, the input clutch 420, the forwardclutch 330, the reverse clutch 332, the disconnect synchronizer 340 andthe park brake or control 430. The DC module 440 communicates with adisconnect synchronizer engagement (DSE) module 450, which in turncommunicates with one or more of a timer module 460, a speed module 470,a pressure module 480 and a values data store 490. The DSE module 450also communicates with a user interface (UI) module 452, which receivesinput from the operator control 418. As illustrated, the timer module460 receives input data from the clock 410, the speed module 470receives sensor input data from the speed sensors 412, 413, 414, and thepressure module receives sensor input data from the pressure sensor 416.The values data store 490 is a memory storage module containing variousstored values used by the controller 402 through one or more of itsmodules to execute control logic according to one or more actual orsensed parameters. The values data store 490 may include one or morespeed, pressure, time or other threshold values which the controller 402may evaluate with respect to actual or sensed parameters according tostored control logic, which may be stored in the various modules orsub-modules, or other onboard or remote memory modules. Example controllogic executed by the controller 402 with respect to the transmission100 or the reverser apparatus 300 will now be described.

FIG. 12 illustrates a flow chart for control logic by which the controlsystem 400 implements a method of executing a start-up mode or sequencefor the transmission 100 or the reverser apparatus 300, according to oneembodiment. Generally, the start-up sequence applies power to thedisconnect synchronizer 340 and thereby torque to itsengagement-effecting components (e.g., shift collar, blocking ring) tofacilitate engagement with the third reverse gear 320. It should benoted that the example method and control logic depicted with respect toFIG. 12, and any of the other various FIGURES, may be applicable to oneor more other embodiments described herein.

The start-up sequence begins at step 500 in which the park brake orcontrol 430 is engaged and all clutches (i.e., the input clutch 420, theforward clutch 330, the reverse clutch 332, etc.) are disengaged priorto or during initial start-up the vehicle. At steps 502 and 504, thecontroller 402, via the DC module 440, energizes or pulses the inputclutch 420 and the reverse clutch 332 to engage such that power (i.e.,rotational force or torque) from the power source is applied,simultaneously or near simultaneously, to both the output shaft 302 andthe counter shaft 306. At step 506, the controller 402, via the timermodule 460, queries whether the input clutch 420 and the reverse clutch332 are disengaged by evaluating input from the clock 410 and a storedpulse duration value or range of values from the values data store 490.In alternative embodiments, rather than using clock input, thisdetermination may be made by the controller 402 using temperature inputdata from temperature sensors at the input clutch 420 and the reverseclutch 332 and stored temperature threshold value or range of valuescorrelated to indicate the engagement period of the clutches. In eithercase, depending on the determination made by the controller 402, thecontrol logic reverts to steps 502 and 504 to continue energizing theinput clutch 420 and the reverse clutch 332, or if the pulse durationhas expired, the method continues to step 508, at which the controller402, via the DC module 440, commands the disconnect synchronizer 340 toengage. At step 510, the controller 402, again via the DC module,commands the forward clutch 330 to engage. At step 512, the start-upsequence of the transmission 100 or reverser apparatus 300 completes,according to one embodiment. In other embodiments, one or more of thesesteps or operations may be omitted, repeated, or re-ordered and stillachieve the desired results.

FIG. 13 illustrates a flow chart including control logic by which thecontrol system 400 implements a method of shifting between a forwardmode and a reverse mode in the transmission 100 or the reverserapparatus 300, according to one embodiment. At step 520, the methodstarts, and at step 522, the controller 402, via the DC module 440, haspreviously commanded the forward clutch 330 to engage, such that thetransmission 100 is in the forward mode F. (At step 522, the controller402 may also engage a countershaft brake if present.) At step 524, thecontroller 402 receives a reverse command, via the UI module 452 and theoperator control 418, and commands, via the DC module 440, thetransmission 100 or the reverser apparatus 300 to switch from theforward mode F to the reverse mode R. (The controller 402 would command,via the DC module 440, a countershaft brake, if present, to disengage,which allows the counter shaft 306 to rotate.) At step 526, the controllogic proceeds to the sub-routine illustrated in FIG. 13A to engage thedisconnect synchronizer 340, according to one embodiment, which isdetailed in the following paragraphs. With the disconnect synchronizer340 engaged, at step 528, the controller 402, via the DC module 440,commands the forward clutch 330 to disengage which disconnects theoutput gear 312 from the output shaft 302, allowing the output gear 312to rotate independently of the output shaft 302, and in which case, thecounter shaft 306 rotates in the opposite direction as the output shaft302. At step 530, the controller 402, via the DC module 440, commandsthe reverse clutch 332 to engage which releasably connects the secondreverse gear 318 to the counter shaft 306. This causes the counter shaft306 to rotate in the same direction as the output shaft 302 based uponthe engagement of the first reverse gear 310 mounted on the output shaft302 with the idler gear 316 mounted on the idler shaft 304 and theengagement of the idler gear 316 with the second reverse gear 318. Atstep 532, the method of shifting between a forward mode and a reversemode in a transmission reverser completes, according to one embodiment.In other embodiments, one or more of these steps or operations may beomitted, repeated, or re-ordered and still achieve the desired results.

FIG. 13A illustrates a flow chart for a subroutine to engage thedisconnect synchronizer 340, according to one embodiment. Generally, theillustrated control logic controls engagement of the disconnectsynchronizer 340 to releasably connect the third reverse gear 320 to thecounter shaft 306, and thereby control engagement of the third reversegear 320 with the output gear 312 in a controlled manner that may reducethe occurs of gear clash or other wear on the disconnect synchronizer340, and the reverser apparatus 300 and the transmission 100 overall.

At step 540, the subroutine begins by the controller 402, via the DCmodule 440 and the DSE module 450, commanding pressure to the disconnectsynchronizer 340. The commanded pressure is limited to an initialpressure value or range of pressure values stored in the values datastore 490 less than the maximum pressure or other operational pressurevalue of the system. The controller 402 may command the full initialpressure immediately. However, in the illustrated example, thecontroller 402, via the DC module 440 and the DSE module 450 as informedby the pressure module 480 and the values data store 490, commands thepressure to ramp up in a linear (or possibly non-linear) manner over aprescribed initial ramp time period (which may be a value or range oftime or counter values stored in the values data store 490). At step542, the controller 402, via the DSE module 450 as informed by the timermodule 460, the pressure module 480, which receives input from thepressure sensor 416, and the values data store 490, queries whether theinitial pressure has been reached. If not, the control logic reverts tostep 540 and continues to increase pressure to the disconnectsynchronizer 340 until the initial pressure value is reached.

At step 544, upon reaching the initial pressure value, the controller402 commands the pressure to the disconnect synchronizer 340 to hold atthe initial pressure value to confirm synchronization of the disconnectsynchronizer 340. To accomplish this, at step 546, the controller 402,via the DSE module 450 as informed by the speed module 470, the speedsensors 412, 414, and the values data store 490, queries whether anengagement slip threshold has been met. The engagement slip thresholdmay be a stored value or range of slip values or other values (e.g.,rotational speed values or ranges) that indicate engagement of thedisconnect synchronizer 340, such as rotational speeds or one or moredifferential speeds across the disconnect synchronizer 340. Thecontroller 402, via the DSE module 450 as informed by the speed module470 and the values data store 490, may resolve the slip across thedisconnect synchronizer 340 by evaluating speed input signals from thespeed sensors 412, 414. By way of example, the speed sensor 412 maysense the rotational speed of the third reverse gear 320 and the speedsensor 414 may sense the rotational speed of the drum 342. In otherembodiments, the speed sensors 412, 414 may sense other components thatrotate relative to one another at some point during operation of thedisconnect synchronizer 340 (e.g., the counter shaft 306 or the hub 350and the shift collar 348).

If the slip corresponding to the sensed rotational speed differentialacross the disconnect synchronizer 340 is higher than the stored slipthreshold value, then the controller 402 continues to hold pressure tothe disconnect synchronizer 340 at the initial pressure as it attemptsto confirm that synchronization has been completed. Specifically, in theexample subroutine illustrated, at step 548, the controller 402, via thetimer module 460 (and clock 410), initiates a timer or counter of theelapsed time period since a synchronization attempt has been commenced,for example, the elapsed time beginning when, or when the controller 402determined that, the disconnect synchronizer 340 reached the initialpressure. At step 550, the controller 402, via the DSE module 450 asinformed by the timer module 460 (and clock 410) and the values datastore 490, queries whether a stored prescribed time period allotted forsynchronization has expired. If the controller 402 determines step 550to be true (i.e., synchronization timed out), then the control logicflows to step 554 at which the controller 402, via the DC module 440,commands the park brake or mode 430 to engage (and otherwise cause thetransmission or vehicle to enter a park mode). If step 550 is false,then the control logic reverts to step 544 after which the controller402 again checks for synchronization (i.e., engagement) of thedisconnect synchronizer 340.

When engaged, at step 556, the controller 402, via the DC module 440,commands a final pressure to the disconnect synchronizer 340. Thecommanded pressure may be a maximum or other higher operational pressurevalue or range of pressure values that may be stored in the values datastore 490. The controller 402 may command the full final pressureimmediately. However, in the illustrated example, the controller 402,via the DC module 440 and the DSE module 450 as informed by the pressuremodule 480 and the values data store 490, commands the pressure to rampup in a linear (or possibly non-linear) manner over a prescribed finalramp time period (which may be a value or range of time or countervalues stored in the values data store 490). At step 558, the controller402, via the DSE module 450 as informed by the timer module 460, thepressure module 480 (and the pressure sensor 416), and the values datastore 490, queries whether the final pressure has been reached. If not,the control logic reverts to step 556 and continues to increase pressureto the disconnect synchronizer 340 until the initial pressure value isreached. When the final pressure has been reached, then the subroutinecompletes, and the above-described method continues at step 528 of FIG.13.

FIG. 14 illustrates a flow chart including control logic by which thecontrol system 400 implements a method of shifting between a reversemode and a forward mode in the transmission 100 or the reverserapparatus 300, according to one embodiment. At step 560, the methodstarts, and at step 562, the controller 402, via the DC module 440, haspreviously commanded the reverse clutch 332 and the disconnectsynchronizer 340 to engage, such that the transmission 100 is in thereverse mode R. At step 564, the controller 402 receives a forwardcommand, via the UI module 452 and the operator control 418, andcommands, via the DC module 440, the transmission 100 or the reverserapparatus 300 to switch from the reverse mode R to the forward mode F.At step 566, the controller 402, via the DC module 440, commands thereverse clutch 332 to disengage which disconnects the second reversegear 318 from the counter shaft 306 (or disconnects the first reversegear 310 from the output shaft 302 in an alternate embodiment) allowingthe counter shaft 306 to rotate independently of the output shaft 302.At step 568, the controller 402, via the DC module 440, commands theforward clutch 330 to engage which releasably connects the output gear312 to the output shaft 302 causing the output gear 312 to rotate withthe output shaft 302. This causes the counter shaft 306 to rotate in thesame direction as the output shaft 302 based upon the engagement of thefirst reverse gear 310 mounted on the output shaft 302 with the idlergear 316 mounted on the idler shaft 304 and the engagement of the idlergear 316 with the second reverse gear 318. At step 570, the controllogic proceeds to the sub-routine illustrated in FIGS. 14A and 14B,according to one embodiment, which is detailed in the followingparagraphs. At step 572, the method of shifting between a reverse modeand a forward mode in a transmission reverser completes, according toone embodiment. In other embodiments, one or more of these steps oroperations may be omitted, repeated, or re-ordered and still achieve thedesired results, for example, the controller 402 may command acountershaft brake (if present) to engage to slow or stop rotation ofthe counter shaft 306 at certain times when in the forward mode F.

FIG. 14A illustrates a flow chart for a subroutine to resolve engagementor disengagement of the disconnect synchronizer 340, according to oneembodiment. Generally, the illustrated control logic controls engagementand disengagement of the disconnect synchronizer 340 to releasablyconnect the third reverse gear 320 to the counter shaft 306, and therebycontrol engagement of the third reverse gear 320 with the output gear312. The illustrated control logic further provides for efficientoperation of the transmission or vehicle by intelligently managing thestate of engagement of the disconnect synchronizer 340, for example, toengage the disconnect synchronizer 340 at certain operational conditionsto achieve rapid forward/reverse shifting within little or no lag, anddisengaging the disconnect synchronizer 340 at other operationalconditions to reduce wear and power consumption associated with itsengagement.

At step 540, the subroutine begins by the controller 402, via the DSEmodule 450 as informed by the speed module 470, querying whether thetransmission 100 or the reverser apparatus is operating below aprescribed first speed threshold, which may be a stored speed value orrange of values stored in the values data store 490. It should beunderstood that the prescribed speed threshold may correspond to one ormore rotational or linear speeds associated with the transmission 100 orthe reverser apparatus 300, or a vehicle in which they are incorporated.Thus, the speed may be determined by the speed module 470 receivingsensed speed signals from various rotational or linear speed sensingdevices, including the speed sensors 412, 413, 414, which may sense thespeeds of various components of the transmission 100 or the reverserapparatus 300 or other components of a vehicle in which they areincorporated, as well as a vehicle ground speed device (e.g., aspeedometer and the like). In any case, the sensed speed and the storedspeed thresholds may be, or may be processed by the controller 402 orother controllers, to correlate to a ground speed value. For example,the control logic in the illustrated subroutine may be useful inmanaging the state of engagement of the disconnect synchronizer 340 withrespect to one or more ground speed values (e.g., relatively low groundspeed values such as <5 kph) and thus the following description of theexample control logic will thus be understood in at least such acontext. Further, since ground speed can be sensed or correlated using asingle sensor (e.g., sensor 413 configured to sense the speed of theoutput gear 312) will be referenced below and in FIG. 14A.

If the controller 402 determines that the speed is below the first speedthreshold, then the control logic dictates engagement of the disconnectsynchronizer 340, and effects this, at step 582, by first queryingwhether the disconnect synchronizer 340 is currently engaged. If not, atstep 584, the controller 402, via the DC module 440 and the DSE module,commands engagement of the disconnect synchronizer 340, and otherwisereverts to step 580 to again query the speed. This continues until step580 is false, and thus specifies that the method of FIG. 14 will controlthe vehicle in the forward mode F to maintain engagement of thedisconnect synchronizer 340 at low speeds (e.g., <3 kph). This readies,and effectively preselects, the reverser arrangement 300 to shift intothe reverse mode R, without requiring a period of zero power during theshift transition, since engagement of the disconnect synchronizer 340happens while out of the power flow of the transmission 100 or thereverser apparatus 300.

At step 586, upon surpassing the first speed threshold, the controller402, via the speed module 470 and the values data store 490, queries thespeed with respect to a stored prescribed second speed threshold thatis, or corresponds to, a higher speed value or range of values than thefirst speed threshold. It should be noted that the controller 402evaluates the second speed threshold at least in part to accommodatehysteresis in the sensed speed signals such that the second speedthreshold may be close in magnitude to (e.g., 4 kph), and provide anupper bound for, the first speed threshold. In fact, in alternateembodiments of the control logic for applications with low or negligiblehysteresis or which do not account for hysteresis, the second speedthreshold may be omitted. In any event, if the speed is below the secondspeed threshold the control logic reverts to 582 where the state of thedisconnect synchronizer 340 is queried and the speed is reassessed withrespect to the first and second speed thresholds.

At step 588, with the speed above the second speed threshold, thecontroller 402 again queries the state of engagement of the disconnectsynchronizer 340. If the disconnect synchronizer is engaged, at step590, the controller 402 initiates a timer or counter via the timermodule 460 (and clock 410), of the elapsed time period above the secondspeed threshold. At step 592, the controller 402, via the DSE module 450as informed by the timer module 460 (and clock 410) and the values datastore 490, queries whether a stored prescribed time period (e.g., 30seconds) allotted for engagement of the disconnect synchronizer 340above the second speed threshold has expired. If not, at step 594, in asimilar manner as in steps 580 and 586 (i.e., by comparing sensed speedwith stored speed threshold values), the controller 402 queries whetherthe speed is above a prescribed third speed threshold stored in thevalues data store 490 as an associated value or range of values. Thethird speed threshold is higher than the second threshold and maycorrespond to a higher speed (e.g., 20 kph) operation of the vehicle inthe forward mode F. If less than the third speed threshold, the controllogic reverts to step 590 at which the timer continues to run and thecontroller 402 again checks time and speed thresholds. If the controller402 determines step 588 to be false, or either of steps 592 or 594 to betrue (i.e., above either the time or speed thresholds), then the controllogic flows to step 596 at which the controller 402, via the DC module440 and the DSE module 450, commands the disconnect synchronizer 340 todisengage. This subroutine completes and the method of FIG. 14 continueswith the subroutine illustrated in FIG. 14B.

FIG. 14B illustrates a flow chart for a subroutine to determine thepresence of a disengagement fault at the disconnect synchronizer 340,according to one embodiment. At step 600, the controller 402, via theDSE module 450 as informed by the speed module 470, the speed sensors412, 414, and the values data store 490, queries whether there is aspeed differential (or slip) across the disconnect synchronizer 340.This may be done by evaluating the sensed speed signals from the speedsensors 412, 414 with respect to each other, or by comparing them to aspeed threshold differential or slip threshold value or range of valuesin the values data store 490. As previously described, to determine aspeed differential across the disconnect synchronizer 340, the speedsensor 412 may sense the rotational speed of the third reverse gear 320and the speed sensor 414 may sense the rotational speed of the drum 342.In other embodiments, the speed sensors 412, 414 may sense othercomponents that rotate relative to one another at some point duringoperation of the disconnect synchronizer 340 (e.g., the counter shaft306 or the hub 350 and the shift collar 348).

If no speed differential is determined at step 600, at step 602, thecontroller 402, via the DC module 440 and the DSE module 450,momentarily energizes or pulses the reverse clutch 332, whichmomentarily applies power to the disconnect synchronizer 340 via thecounter shaft 306 (momentarily four-squaring the transmission) to verybriefly apply torque to disengage certain components (e.g., shift collarand gear cone) that may have been maintained in engagementinadvertently. At step 604, the controller 402 again checks for adifferential speed across the disconnect synchronizer 340 in the samemanner as step 600. If due to the pulsing at step 602 or for otherreasons, a speed differential exists and disengagement is confirmed,then the subroutine completes and returns to step 572 in the method ofFIG. 14, at which the method of shifting between a reverse mode and aforward mode in a transmission reverser completes, according to oneembodiment. If not, the controller, via the DC module 440, commandsengagement of the park brake or mode 430.

It will be appreciated that when the disconnect synchronizer 340 isdisengaged the counter shaft 306, and thereby the reverse clutch 332, isdisconnected from the output gear 312. In this condition, differentialspeed across the disengaged reverse clutch 332 that would have existedwithout this disconnection is eliminated, along with associated wearfrom the various effects of windage, gyroscopic flutter and other dragthat may arise between the relatively rotating elements of thedisengaged reverse clutch 332. Avoiding such effects, which may beparticularly deleterious should the transmission be operated beyondcertain maximum design parameters (e.g., when the vehicle is operated atexcessive speeds by gravity), improves the operational life of thereverse clutch 332, and thus the transmission 100 and the reverserapparatus 300 overall.

The control logic of the illustrated subroutines has been described withrespect to the methods of FIGS. 13 and 14 with the subroutine of FIG.13A being described with respect to a reverse mode R and the subroutinesof FIGS. 14A and 14B being described with respect to a forward mode F.It will be understood that the subroutines may be implemented intransmissions or reverser apparatuses operating in different modes oraccording to other methods or control logic.

Without in any way limiting the scope, interpretation, or application ofthe claims appearing below, a technical effect of one or more of theexample embodiments disclosed herein is a double disconnect transmissionreverser for changing the direction of a vehicle between forward andreverse. Another technical effect of one or more of the exampleembodiments disclosed herein is a transmission reverser which reduceswindage or friction in a disengaged reverse clutch. Another technicaleffect of one or more of the example embodiments disclosed herein is atransmission reverser which reduces the possibility of gyroscopicflutter in the disengaged reverse clutch due to lower rotational speeds.Another technical effect of one or more of the example embodimentsdisclosed herein is a transmission reverser which can impede or preventcounter rotation of the reverse clutch during high forward speeds of thevehicle.

The terminology used herein is for the purpose of describing particularembodiments or implementations and is not intended to be limiting of thedisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the any use ofthe terms “having,” “including,” “comprising,” or the like, in thisspecification, identifies the presence of stated features, integers,steps, operations, elements, and/or components, but does not precludethe presence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

The references “A” and “B” used with reference numerals herein aremerely for clarification when describing multiple implementations of anapparatus.

One or more of the steps or operations in any of the methods, processes,or systems discussed herein may be omitted, repeated, or re-ordered andare within the scope of the present disclosure.

While the above describes example embodiments of the present disclosure,these descriptions should not be viewed in a restrictive or limitingsense. Rather, there are several variations and modifications which maybe made without departing from the scope of the appended claims.

What is claimed is:
 1. A transmission reverser for reversing a directionof an output gear carried by an output shaft, the transmission reversercomprising: a reverse shaft; a reverse clutch mounted about the reverseshaft and having engaged and disengaged conditions; and a reversedisconnect synchronizer mounted about the reverse shaft and havingengaged and disengaged conditions; wherein, when the reverse clutch andthe reverse disconnect synchronizer are in the engaged conditions, thereverse shaft rotates the output gear in a reverse direction of rotationopposite a direction of rotation of the output shaft; and wherein, whenthe reverse disconnect synchronizer is in the disengaged condition, thereverse clutch is disconnected from the output gear.
 2. The transmissionreverser of claim 1, further including: a first reverse gear mounted tothe output shaft; an idler shaft including an idler gear engaged withthe first reverse gear; a second reverse gear engaged with the idlergear; and a third reverse gear mounted about the reverse shaft andengaged with the output gear, the third reverse gear being connected tothe reverse shaft when the reverse disconnect synchronizer is in theengaged condition; wherein, when the reverse clutch and the reversedisconnect synchronizer are in the engaged conditions, the reverse shaftrotates relative to the output shaft based upon ratios of the firstreverse gear to the idler gear and the idler gear to the second reversegear, and the output gear rotates relative to the reverse shaft basedupon a ratio of the third reverse gear to the output gear.
 3. Thetransmission reverser of claim 3, wherein, when in the engagedcondition, the reverse clutch releasably connects the second reversegear with the reverse shaft, and, when the reverse disconnectsynchronizer is in the engaged condition, the reverse clutch releasablyconnects the first reverse gear with the output shaft.
 4. Thetransmission reverser of claim 1, further including: a forward clutchmounted about the output shaft and having engaged and disengagedconditions, the forward clutch releasably connecting the output gearwith the output shaft in the engaged condition; wherein, in a forwardmode in which the reverse clutch is in the disengaged condition and theforward clutch is in the engaged condition, the output gear rotates inthe direction of rotation of the output shaft.
 5. The transmissionreverser of claim 4, wherein the forward mode further includes thereverse clutch in the disengaged condition, and the reverse disconnectsynchronizer in the engaged condition below at least one of a speedthreshold and a time threshold and in the disengaged condition above theat least one speed threshold and time threshold.
 6. The transmissionreverser of claim 1, wherein the reverse disconnect synchronizer is aforkless hydraulic synchronizer.
 7. The transmission reverser of claim6, wherein the reverse disconnect synchronizer has a hub mounted aboutthe reverse shaft defining a piston chamber in which fluid pressuredrives an actuator piston to move a shift collar.
 8. The transmissionreverser of claim 6, further including: a shift collar and a spring;wherein the actuator piston moves the shift collar in one directionalong a rotation axis of the reverse shaft; and wherein the springbiases the actuator piston to move the shift collar in a directionopposite the direction in which the hydraulic fluid drives the actuatorpiston.
 9. The transmission reverser of claim 7, wherein the reversedisconnect synchronizer is a half synchronizer including a singleactuator piston and a single shift collar moved by the actuator pistonin at least one direction along the rotation axis of the reverse shaft.10. The transmission reverser of claim 1, wherein the reverse disconnectsynchronizer has an actuator piston that moves a shift collar in atleast one axial direction of the transmission reverser; wherein theactuator piston has a first annular surface with a first interlockfeature; wherein the shift collar has a second annular surface with asecond interlock feature configured to engage the first interlockfeature of the actuator piston; and wherein the shift collar isconnected to the actuator piston by overlapping radial surfaces of thefirst and second interlock features when the first and second annularsurfaces are arranged concentrically.
 11. The transmission reverser ofclaim 10, wherein coupling the first and second interlock featuresconnects the shift collar and the actuator piston with relativerotational freedom.
 12. The transmission reverser of claim 10, wherein,in at least one condition of the transmission reverser, the radialsurfaces of the first and second interlock features engage to preventseparation of the shift collar from the actuator piston in at least oneaxial direction.
 13. The transmission reverser of claim 10, wherein theradial surfaces are oriented substantially perpendicular to the reverseshaft.
 14. The transmission reverser of claim 10, wherein the first andsecond annular surfaces include respective first and second undercutrecesses adjacent the radial surfaces of the first and second interlockfeatures; and wherein the first and second annular surfaces includerespective first and second chamfered leading edges facing the other ofthe first and second annular surfaces.
 15. The transmission reverser ofclaim 10, wherein the actuator piston is a first material and the shiftcollar is a second material different than the first material.
 16. Thetransmission reverser of claim 10, wherein the first and secondinterlock features are coupled by a press-fit operation of the annularpiston onto the shift collar.
 17. The transmission reverser of claim 10,wherein the annular piston includes one or more peripheral notches at aleading edge of the first annular surface.
 18. A transmission reverserfor reversing a direction of an output gear carried by an output shaft,the transmission reverser comprising: a reverse shaft extending along arotation axis; reverse gears mounted about the reverse shaft; a reverseclutch mounted about the reverse shaft and having engaged and disengagedconditions, the reverse clutch connecting one of the reverse gears withthe reverse shaft in the engaged condition; and a reverse disconnectsynchronizer having engaged and disengaged conditions, the reversedisconnect synchronizer connecting another of the reverse gears with thereverse shaft in the engaged condition, the reverse disconnectsynchronizer including: a hub mounted about the reverse shaft anddefining a piston chamber; an actuator piston within the piston chamberand driven by fluid pressure in at least one direction along therotation axis of the reverse shaft; and a shift collar mounted to theactuator piston and engaging the reverse gear in an engaged state;wherein, when the reverse clutch and the reverse disconnect synchronizerare in the engaged conditions, the reverse shaft rotates the output gearin a reverse direction of rotation opposite a direction of rotation ofthe output shaft; and wherein, when the reverse disconnect synchronizeris in the disengaged condition, the reverse clutch is disconnected fromthe output gear.
 19. The transmission reverser of claim 18, wherein theactuator piston has a first annular surface with a first interlockfeature; wherein the shift collar has a second annular surface with asecond interlock feature configured to engage the first interlockfeature of the actuator piston; wherein the shift collar is connected tothe actuator piston by overlapping radial surfaces of the first andsecond interlock features when the first and second annular surfaces arearranged concentrically.
 20. A transmission reverser for reversing adirection of an output gear carried by an output shaft, the transmissionreverser comprising: a reverse shaft extending along a rotation axis;reverse gears mounted about the reverse shaft; a reverse clutch mountedabout the reverse shaft and having engaged and disengaged conditions,the reverse clutch connecting one of the reverse gears with the reverseshaft in the engaged condition; and a reverse disconnect synchronizerhaving engaged and disengaged conditions, the reverse disconnectsynchronizer connecting another of the reverse gears with the reverseshaft in the engaged condition, the reverse disconnect synchronizerincluding: an actuator piston having a first annular surface with afirst interlock feature; and a shift collar engaging the reverse gear inan engaged state and having a second annular surface with a secondinterlock feature configured to engage the first interlock feature ofthe actuator piston; wherein the shift collar is connected to theactuator piston by overlapping radial surfaces of the first and secondinterlock features when the first and second annular surfaces arearranged concentrically; wherein, when the reverse clutch and thereverse disconnect synchronizer are in the engaged conditions, thereverse shaft rotates the output gear in a reverse direction of rotationopposite a direction of rotation of the output shaft; and wherein, whenthe reverse disconnect synchronizer is in the disengaged condition, thereverse clutch is disconnected from the output gear.